I'm thinking about getting a multi stage or variable speed furnace to go with my fairly new 10 Seer Carrier condensor. Will the AC air handler fan speed be set to a fixed speed because the coil could ice up? Will I only get the benefits of multi speed fan for the heating part? Or maybe, because of the condensor, have to set it to fixed speed for both functions (and therefore should get a single speed furnace)? hmmm Just asking so I don't sound foolish before I talk to the contractors tomorrow. :)
Confused about multi stage or variable speed furnace with non variable condensor
Sep 29, 2008
3 Replies
p.s. I should mention I will be using the Honeywell TH8321U1006 VisionPro thermostat, the one with sophisticated programming for multi stage systems, if this makes answer difference for the answer...
Yes, the multi-stage feature will only work with the heat. Two stage cooling systems also exist, but you need to replace the outdoor unit with a two stage one.
JK
You are confusing the two terms. All gas furnaces ( at least all the major brands) have at least three speed blower motors-- many have four. This is so the system can be "fine tuned" to get the optimum air flow in both heating and cooling. Variable speed motors allow even more adjustment, slowly ramp up to speed, and down on the off cycle. Two stage furnaces mean that they have two firing rates for the heating -- nothing to do with the cooling side. The fact that you have a 10 SEER c/u really doesn't change anything. Whichever inside equipment you choose, it will operate basically the same as though it was all new matched 13 SEER-- except obviously at less electrical efficiency in cooling. HTH Larry
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